The below provided background information and description of prior publications is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the below publications and information provided constitutes prior art against the present invention.
In order to prepare a cased wellbore drilled in a hydrocarbon formation for production, such cased wellbore first needs to be perforated along portions of its length in order for hydrocarbons to flow into such wellbore for pumping to surface.
Prior art apparati and methods for creating perforations in the wellbore casing have typically comprised placing a string of explosive charges, namely shaped charges adapted to explode radially outwardly, within and along a length of the wellbore, and igniting such charges and thereafter withdrawing the perforating string from the wellbore.
Other methods and apparati for creating perforations along a wellbore have involved insertion of a tool having one or more nozzles, adapted to direct radially outwardly therefrom an abrasive fluid under high pressure. Such abrasive high pressure fluid impacts the wellbore casing and due to its abrasive nature, cuts a hole or holes in the wellbore casing. Such tool is moved along the wellbore casing to create additional perforations in such wellbore along a desired length thereof.
Typically, after a wellbore has been perforated, as a means to increase the rate and volume of production from the formation prior to commencing production therefrom a fracking fluid (typically containing proppants, acids, diluents, and/or other flow-stimulating additives) is injected under high pressure into the wellbore in a fracking operation. Typically only portions of a wellbore are “fracked” at a time, requiring a zone of a wellbore that is to be fracked to be isolated from other regions of the wellbore, typically by rubberized packer elements which are actuated by hydraulic pressure.
In such fracking operation, when a particular one or number of perforations along a wellbore are isolated by packers, a high pressure fluid is flowed into the wellbore and thus into the formation in the region of the perforation(s). Such high pressure fluid creates fissures within the formation. The created fissures (typically lines of fracture within the formation) generally emanate radially outwardly from the wellbore and thereby create flow channels in the formation which lead to the wellbore, thereby assisting hydrocarbons to subsequently flow into and be collected by the wellbore.
Unsatisfactorily however, no tool exists that is able to both perforate using abrasive jets, as well as carry out fracking operations without having to use separate tools and trip the tool out, in an effective and efficient manner.
U.S. Pat. No. 4,781,250 to McCormick et al., entitled “Pressure Actuated Cleaning Tool” teaches a downhole tool for cleaning tubing, casing and flow lines with pressurized cleaning fluid pumped through coiled tubing. The cleaning tool is rotated by a “J”-slot indexing tool, which activated by fluid pressure changes and a spring, to effectively rotate the tool 360°. McCormick et al does not, however, disclose any apparati or method on the same tool for further being able to carrying out fracking of the formation via the perforations created by such same tool.
U.S. Pat. No. 7,963,332 to Dotson, entitled “Apparatus and Method for Abrasive Jet Perforating”, teaches a device using an abrasive jet for perforating, with a mechanical locating collar. Such patent however does not teach any sliding sleeve to open and close the perforating jet, nor does it teach use of such perforator jet, in combination with a packers, a bypass, a “j” slot used to set and release a setting tool, and frac ports, all incorporated into and for use by the same tool to permit both perforating and fracking using the same tool.
Likewise, and to similar effect, U.S. Pat. No. 8,757,262 similarly to Dotson, entitled “Apparatus and Method for Abrasive Jet Perforating and Cutting of Tubular Members”, teaches an abrasive jet perforating tool, coupled rotatably to a tubing string, and a horizontal indexing tool coupled thereto. An extension tool with a protective sleeve is used to protect the apparatus. Again, however, such patent fails to disclose any apparati or method on the same tool for further being able to carrying out fracking of the formation via the perforations created by such same tool.
U.S. Pat. No. 5,765,756 by Jordan et al., entitled “Abrasive Slurry Jetting Tool and Method” teaches an abrasive jet perforating tool with telescoping jet nozzles. The jetting nozzles are operated perpendicularly to the longitudinal axis of the tool body, although the nozzle assemblies can pivot back into the tool body for retrieval back up the wellbore. Jordan et al similarly fails to disclose a single tool with further components which allow not only perforation but also setting of the tool to frac as well as perforate, or a method by which fracking and perforation using an abrasive jet may be accomplished by a single tool.
Accordingly, a clear need exists in the wellbore completion industry for a tool which uses abrasive jetting to create perforations in wellbore casings, and which may further accomplish fracking of the formation using the same tool, to thereby save time and speed completion of wellbores in preparation for hydrocarbon production therefrom.
A clear and serious need further exists in fracking operations to provide a tool which is not prone to becoming “sanded-in” within the wellbore. In this regard, a “sanded-in” fracking tool at the end of a frack string cannot be removed after fracking to thereby allow oil production to commence from the completed well.
Specifically, it has been found that fracking tools at the end of a fracking tubing string and which are typically lowered to the bottom of a wellbore and thereafter moved upwardly to successively frac the formation along the wellbore during such upward movement, may frequently, due to the introduction of fracking sand within a fracking mixture at each fracking interval to thereby “prop” open the fractures created in the wellbore to allow better flow of oil, cause the fracking tool becoming “sanded in” within the wellbore and the frac string thus be unable to be removed from the wellbore.
This is a very serious and potential problem if it occurs, as no production of oil can thereafter be achieved. The fracking string will then need to be pulled up with such force that it will break, and a milling tool re-inserted down the wellbore to mill out any remaining sand-entrapped components of the frack string remaining in the well, to thereby clear the well for production.
Obviously, ‘sanding-in’ of fracking tools is a very serious problem as it results in significant lost production time, to say nothing of the time resulting lost time and expense of having to mill out damaged and “sanded-in” frac string components.
A very serious need thus exists for a fracking tool which is able to reliably or better prevent “sanding in” of the tool after one or more successive fracking operations along a wellbore.